In a wireless communication system, an RF modulated signal from a transmitter may reach a receiver via a number of propagation paths. The characteristics of the propagation paths typically vary over time due to a number of factors such as fading and multipath. To provide diversity against deleterious path effects and improve performance, multiple transmit and receive antennas may be used. Generally, diversity increases and performance improves with more transmit (TX) and receive (RX) antennas.
A multiple-input multiple-output (MIMO) communication system can employ multiple (M) transmit antennas and multiple (N) receive antennas for data transmission. A MIMO channel formed by the M transmit and N receive antennas may be decomposed into I independent channels, with I≦min {M, N}. Each of the I independent channels corresponds to a dimension, and may also be referred to as a spatial subchannel (or a transmission channel) of the MIMO channel. The MIMO system can provide improved performance (e.g., increased transmission capacity) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
Every TX antenna in a MIMO system is usually provided with a corresponding TX signal path, which prepares a signal for transmission over the TX antenna. For example, a TX signal path may include RF circuitry for upconverting and amplifying a baseband TX signal. Similarly, every RX antenna in a MIMO system is usually provided with a corresponding RX signal path, which processes the signal received by the RX antenna. For example, a RX signal path may include RF circuitry for amplifying a received signal, and downconverting the signal to baseband for further RX processing.
For each signal path (TX or RX), multiple parameters may need to be configured depending on the particular characteristics of that signal path. For example, one such parameter may be a common-mode voltage trim parameter associated with a low-noise amplifier (LNA) in each RX signal path. Given that there may be multiple such parameters per signal path, and multiple signal paths in a MIMO system, it would be desirable to have efficient techniques to configure all the parameters of all the signal paths in a MIMO system.